This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Background: The presence of retroviral infection in nonhuman primate research animals makes them unsuitable for a number of research studies. In addition, the presence of B-virus in nonhuman primates used in research is a significant occupational safety and health concern. The specific pathogen free (SPF) program was created to provide rhesus monkeys seronegative for SIV, SRV, STLV-1, and B-virus. The majority of the animals assigned to the SPF breeding program are in the NCRR/OAR AIDS colony which limits assignment of animals to AIDS research programs. The base grant supported SPF colony described here allows allocation of SPF animals to other than AIDS studies. Methods: Yearling rhesus are housed with peers from their natal groups while viral screening occurs during years 1-3 and are then moved into larger breeding groups. Animals testing positive for viral agents are removed from the SPF program. Yearling rhesus macaques are currently being removed from the conventional breeding colony for inclusion in the SPF program. Results/Discussion: The colony currently consists of 1027 animals (298 Chinese-origin rhesus and 729 Indian-origin rhesus). In 2010, a total of 145 animals were made available for assignment to core and affiliate researchers. In addition, piggybacked use of animals in the breeding colony occurred. Tissues, including blood, feces, saliva, and bone marrow, were provided to investigators to support their research programs. Behavioral/observational data were also collected to support research and management programs. All piggyback use of animals is noninvasive or minimally invasive and allows animals to remain in their social groups with no impact to production.